In many applications such as in aircraft, passenger viewing windows may be made from optically transparent polymers such as acrylic, rather than glass which is relatively heavy, brittle and may be difficult to form into complex shapes. Polymer windows are also desirable for aircraft applications because they are somewhat flexible and resilient, allowing them to withstand impact loads such as bird strikes. However, because of their relative flexibility, polymer windows may be more efficient than glass windows in transmitting sounds outside the aircraft into interior cabin spaces. Symmetrically shaped polymer windows may be especially efficient at amplifying and transmitting sound in the 100-500 Hz frequency range. One solution to the problem consists of increasing the thickness of the polymer window, however this solution may be undesirable in some applications because the increase in window thickness adds weight to the aircraft.
Accordingly, there is a need for a polymer window that is effective in reducing sound transmission without substantially increasing its weight, while maintaining the quality of its optical transparency. There is also a need for a method of fabricating such a window that is efficient, economical, and well suited to higher production environments.